Elbows, etc., on vents; need an expert opinion! - Page 6
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  1. #66
    Join Date
    Jun 2004
    Posts
    459
    Doesn't look as bad as what I'd thought reading the text! Let's make this simple, first off, count a 45º fitting as ½ of a 90ºelbow. It takes 2-45º fittings to equal 1 90º elbow. The one mistake I see from the pics is that the second transition is in a horizontal section of pipe; that leads to a trap for condensate, which in effect reduces your inside diameter of the 2" pipe. NOT GOOD! Rules for transitions: (a)must be located outside of furnace cabinet;(b)must be installed in verticle sections of pipe.

    last observation: why in the world did they start out with 2" to 3" back to 2"???? that's crazy!

    It looks to me that all fittings are of the long radius type, which is a good thing.

    Happy heating!

  2. #67
    Join Date
    Nov 2002
    Posts
    230
    Originally posted by re2ell
    Doesn't look as bad as what I'd thought reading the text! Let's make this simple, first off, count a 45º fitting as ½ of a 90ºelbow.
    No! The mfr (plus my own experience) count 45° as 1 elbow. It is stated in the instructions - period. Read the chart posted on page two of this thread also.

  3. #68
    Join Date
    Jun 2004
    Posts
    459

    vent issue

    I'm to be corrected! Your 3" to 2" transition in the horizontal run is good to hunt without any concern for condensate entrapment. Looks to me the appearence is questionable, you shouldn't have any problems with your heating system.

  4. #69
    Join Date
    Jan 2006
    Location
    Minneapolis, MN
    Posts
    70
    FYI, I spoke with the company rep and explained my unhappiness. He agreed to consider changes in the venting system, so I emailed pics and a diagram. It's getting down to -15 tonight, so he is swamped with "no heat" calls right now. Does this always happen during cold snaps? Do you pros hate cold snaps (too busy) or love them (lots of work and $)? I believe we'll be able to resolve all of this by next week. I will post the outcome and wish to thank all of you, again. You are a great service!

  5. #70
    Join Date
    Jul 2002
    Posts
    962
    Jeff-4,

    I am glad you feel, that there are more important things to worry about than the color of primer they use. Some guys here like to brag how good they are and get carried away with these type of things. It really doesn't matter, and its better to know that primer was used. After all it is a un-finished basement for cry sake.

  6. #71
    Join Date
    Jun 2004
    Posts
    459

    venting

    wow! just noticed that cumbustion air is drawn from inside the house!!!! Major, Major, no, no! Unless the installers got very fancy restrictions on the air-intake, seems to me the flames should be lifting off the burners from too much combustion air entering.

    If a breakdown is going to happen, there is a good source for major problems!

  7. #72
    Join Date
    Jan 2006
    Location
    Minneapolis, MN
    Posts
    70

    Re: venting

    Originally posted by re2ell
    wow! just noticed that cumbustion air is drawn from inside the house!!!! Major, Major, no, no! Unless the installers got very fancy restrictions on the air-intake, seems to me the flames should be lifting off the burners from too much combustion air entering.

    If a breakdown is going to happen, there is a good source for major problems!
    This seems like the thread that will never end...

    I'm not sure what you mean by "cumbustion air is drawn from inside the house." There is a 6" vent that comes from directly outside the house and terminates in the equipment room (no restrictions on it, other than screens to keep critters out). It feeds combustion air to the hot water heater and the furnace (installed in a Non-Direct vent configuration). I am no pro, but this is a configuration that is listed in the installation manual, so I think it is OK.

  8. #73
    Join Date
    Jun 2004
    Posts
    459

    venting

    Sorry to alarm you about combustion air entering from inside. By good design practices, it is best to pull the combustion air from the same vicinity as the exhaust air, due to pressure differential of the air. Also, from the standpoint of heating effeciency, the less outside air introduced into a structure, the less heat energy required to bring that air up to comfort levels.......suppose its all a matter of preference over allowable.

  9. #74
    Join Date
    Mar 2004
    Location
    Cabot, PA
    Posts
    177

    r2 get a grip....

    Read the whole thread before you post. First off the Mfg allows for a one pipe install on this unit if venting VERTICAL. Secondly the HO Has already posted pic showing outside air ducted into furnace room. So know the facts before you start posting things that might needlessly alarm the public.

  10. #75

    Re: venting

    [QUOTE]Originally posted by re2ell
    [B]Sorry to alarm you about combustion air entering from inside. By good design practices, it is best to pull the combustion air from the same vicinity as the exhaust air, due to pressure differential of the air.

    What is you talking about? From what book are you quoting from. I got my info from mechanical code 2006. Combustion air can be taken from any where except contaminated places.

    regards,
    Kelvin

  11. #76
    Join Date
    Jun 2004
    Posts
    459
    Sorry to alarm you about combustion air entering from inside. By good design practices, it is best to pull the combustion air from the same vicinity as the exhaust air, due to pressure differential of the air. Also, from the standpoint of heating effeciency, the less outside air introduced into a structure, the less heat energy required to bring that air up to comfort levels.......suppose its all a matter of preference over allowable.


    Kelvin, thanks for the input! I should not have brought up the pressure differential issue, period. However, the point I would like to highlight is "the less outside air introduced into a structure, the less heat energy required to bring that air up to comfort levels......." My source of information is from ACCA Load Calculation Manual J....

    Ventilation Air
    If mechanical ventilation is used to introduce outside air into the structure, the heat required to temper the air can be calculated as follows:

    Q = 1.1xCFMx(RAT-OAT).
    Where:
    Q = heat to temper the air Btuh
    1.1 = a constant
    CFM = cu. ft./min of air introduced by the equipment
    RAT = room air temperatureºF
    OAT = outside design air temperatureºF


    Again Kelvin, thanks a million, I'll be more carefull in the future!

  12. #77
    Join Date
    May 2004
    Posts
    368
    Kelvin, I hope that the date of your code book is a typo. 2006 hasn't been issued for Michigan as yet we are still under 2003. You should try to join us at the next Michigan HVAC-Talk Chapter meeting, whenever that comes along, and we could discuss certain allowable and non allowed uses of combustion air and when and where you can really get it from.
    Vern P: 2003 MBC,MRC,IFGC,IFC
    An HVAC-Talk Michigan Chapter Mechanical Inspector, Jurisdiction-Ann Arbor

  13. #78
    Join Date
    Apr 2004
    Posts
    7,680
    Dont confuse combustion air with ventilation air, they are not the same.

    The OP needs to have it corrected to 3". I wouldnt press the contractor during a cold snap unless your unit has a problem during the cold snap, I am sure appreciates your patients. If you do have a problem, they better come prepared to make it right. And once the cold snap settles, he needs to know that you become a priority.

    OP... is there a reason you cant sidewall vent right out there? (Driveway or something?) I'm a little concerned they will have a hard time sticking a 3" pipe up through that wall.

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